A driver circuit for providing a regulated current (i.e., a constant current source) to a load must be able to determine the actual current provided to the load in order to accurately regulate the current. A ground referenced signal indicative of the actual current is required because most electronic circuits and devices operate based on ground referenced signals. In a driver circuit topology where the load can be adequately powered by an input voltage to the driver circuit (e.g. a voltage required at the load to maintain the regulated current is less than the input voltage), a resistor can be placed between ground and a negative terminal of the load such that a voltage at the negative terminal of the load provides the ground referenced signal indicative of the current through the resistor and the load.
For loads that require a voltage higher than the input voltage to the driver circuit to maintain the regulated current in the load, the driver circuit must include a direct current (DC) to DC converter. The DC to DC converter may be a fly back converter, a buck boost converter, a blocking boost converter, or any other type of converter for providing DC power. In this driver circuit topology, the load is connected between a positive and a negative terminal of the converter, not connected between the positive terminal of the converter and ground. Therefore, connecting a resistor between the load and ground does not provide a ground referenced signal indicative of the actual current provided to the load. Integrated circuit solutions are available for providing a ground referenced signal proportional to the actual current provided to the load, but these circuits are cost prohibitive in many applications. For example, a driver circuit for powering light emitting diode (LED) lighting in a vehicle cannot feasibly include this integrated circuit solution due to the additional cost.